Certain types of motor vehicles such as four wheel drive sport utility vehicles, light trucks, agricultural vehicles, watercraft, all-terrain, military vehicles and mining vehicles at times may be operated in off-road areas. Such vehicles can typically have engine sizes of under 1 liter to more than 20 liters piston displacement, and horsepower of less than 10 to more than 1500 (7.5-1118 kw). In this off-road environment, vehicles may encounter liquid obstacles, such as rivers, streams, water-filled ditches, or water-filled ravines.
Crossing these liquid obstacles can have serious consequences if the depth of the liquid is deeper than the height of the engine air intake on the vehicle. If more than just a small amount of water enters the engine air intake, engine damage may occur. Such damage may include hydrostatic lock. If an engine cylinder gets more water in it than its compressed volume, the engine stops instantly and major engine damage, such as bent piston connecting rods may result.